Pneumatic conveying systems of the kind having several inlet points for conveyed material normally include valves controlling the discharge of material from each of the inlets and into a transport pipe net. Valves having such a function will in this specification be referred to as “discharge valves”. Such pneumatic conveying systems involve a few typical situations when the behavior of the discharge valves needs to be individually configured with respect to operation time. This individual valve configuration normally includes setting a time/delay before opening a first discharge valve of a branch after activating the branch by generating air flow therein. The individual time/delay configuration of the discharge valves of the material inlets serves to ensure appropriate transport airspeed in the branch. In the case of a system involving several branches the set time/delay for the first discharge valve of each branch starts after switching active branch by opening the appropriate air inlet valve. The individual valve configuration may further include setting a proper time/delay between consecutive openings of discharge valves in order to avoid overloading the system.
Presently, both of the above mentioned operation times/delays are normally individually configured for each branch of a multiple branch system and thus for each valve depending on its localization along the transport pipe net and also depending on its typical material production ratio. Optimization of a system configuration with respect to efficiency—may in this field be specified as energy per amount of transported material—involves finding as low time/delay values as possible without interfering with safe material transport. Any static or predefined configuration must have built-in compensation for “worst-case” situations and variations and will have sub-optimal efficiency under average working conditions.
WO 2011/108971 A1 discloses sensors provided in direct association with a storage space of a pneumatic material collection and transport system. The sensors are of a type suitable for detecting waste remaining in a storage space. They are used to detect when a storage space has been adequately emptied so that its discharge valve may be closed and an emptying cycle of a next storage space in a system emptying sequence may be initiated with minimum delay.